[dpdk-dev] [PATCH v5 00/23] Add DLB2 PMD

McDaniel, Timothy timothy.mcdaniel at intel.com
Fri Oct 30 12:58:41 CET 2020



> -----Original Message-----
> From: McDaniel, Timothy
> Sent: Friday, October 30, 2020 5:17 AM
> To: Thomas Monjalon <thomas at monjalon.net>
> Cc: dev at dpdk.org; Carrillo, Erik G <Erik.G.Carrillo at intel.com>; Eads, Gage
> <gage.eads at intel.com>; Van Haaren, Harry <harry.van.haaren at intel.com>;
> jerinj at marvell.com; david.marchand at redhat.com
> Subject: RE: [PATCH v5 00/23] Add DLB2 PMD
> 
> > -----Original Message-----
> > From: Thomas Monjalon <thomas at monjalon.net>
> > Sent: Friday, October 30, 2020 5:02 AM
> > To: McDaniel, Timothy <timothy.mcdaniel at intel.com>
> > Cc: dev at dpdk.org; Carrillo, Erik G <erik.g.carrillo at intel.com>; Eads, Gage
> > <gage.eads at intel.com>; Van Haaren, Harry <harry.van.haaren at intel.com>;
> > jerinj at marvell.com; david.marchand at redhat.com
> > Subject: Re: [PATCH v5 00/23] Add DLB2 PMD
> >
> > 30/10/2020 10:43, Timothy McDaniel:
> > > - note that the code still uses its private byte-encoded versions of
> > >   umonitor/umwait, rather than the new functions in the power
> > >   patch that are built on top of those intrinsics. This is intentional.
> >
> > Why? Now these intrinsics are available in the main branch.
> > We should avoid duplicating such code.
> >
> >
> 
> I had asked that the low level intrinsics (UMWAIT/UMONITOR) be split out so
> that DLB/DLB2 could use them instead of its own private byte-encoded versions,
> but instead we have these wrappers that call the low level intrinsics. Those
> wrappers
> introduce additional overhead that is not required for DLB/DLB2. I have a
> meeting with Ma Liang on Monday to discuss.

I thought the ask of DLB was to just substitute the low level umwait/umonitor byte
encoded instructions DLB has defined privately with similar byte-encoded instructions defined in the power
patch. The power patch does not directly expose those, which is why I did not update DLB/DLB2.
The power patch does have the advantage of centralizing the race avoidance
logic, which is a good thing for any PMD that wishes to take advantage of umwait/umonitor.  

Sorry for the confusion. I just misunderstood what was being asked of DLB in regard to switching over..  That being said, 
I am willing to convert DLB/DLB2 to use  rte_power_monitor(...) in a future patch-set.

Thanks,
Tim




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